title: Can procalcitonin help identify associated bacterial infection in patients with severe influenza pneumonia? A multicentre study.
abstract: OBJECTIVE
  To determine whether procalcitonin (PCT) levels could help discriminate isolated viral from mixed (bacterial and viral) pneumonia in patients admitted to the intensive care unit (ICU) during the A/H1N1v2009 influenza pandemic.
  
  
  METHODS
  A retrospective observational study was performed in 23 French ICUs during the 2009 H1N1 pandemic. Levels of PCT at admission were compared between patients with confirmed influenzae A pneumonia associated or not associated with a bacterial co-infection.
  
  
  RESULTS
  Of 103 patients with confirmed A/H1N1 infection and not having received prior antibiotics, 48 (46.6%; 95% CI 37-56%) had a documented bacterial co-infection, mostly caused by Streptococcus pneumoniae (54%) or Staphylococcus aureus (31%). Fifty-two patients had PCT measured on admission, including 19 (37%) having bacterial co-infection. Median (range 25-75%) values of PCT were significantly higher in patients with bacterial co-infection: 29.5 (3.9-45.3) versus 0.5 (0.12-2) μg/l (P < 0.01). For a cut-off of 0.8 μg/l or more, the sensitivity and specificity of PCT for distinguishing isolated viral from mixed pneumonia were 91 and 68%, respectively. Alveolar condensation combined with a PCT level of 0.8 μg/l or more was strongly associated with bacterial co-infection (OR 12.9, 95% CI 3.2-51.5; P < 0.001).
  
  
  CONCLUSIONS
  PCT may help discriminate viral from mixed pneumonia during the influenza season. Levels of PCT less than 0.8 μg/l combined with clinical judgment suggest that bacterial infection is unlikely.
authors.affiliation: Service de Réanimation médicale, Medical Intensive Care Unit, Université Paris-Est Créteil, Créteil, France.
authors.forename: E
authors.initials: E
authors.lastname: Cuquemelle
authors.forename: F
authors.initials: F
authors.lastname: Soulis
authors.forename: D
authors.initials: D
authors.lastname: Villers
authors.forename: F
authors.initials: F
authors.lastname: Roche-Campo
authors.forename: C
authors.initials: C
authors.lastname: Ara Somohano
authors.forename: M
authors.initials: M
authors.lastname: Fartoukh
authors.forename: A
authors.initials: A
authors.lastname: Kouatchet
authors.forename: B
authors.initials: B
authors.lastname: Mourvillier
authors.forename: J
authors.initials: J
authors.lastname: Dellamonica
authors.forename: W
authors.initials: W
authors.lastname: Picard
authors.forename: M
authors.initials: M
authors.lastname: Schmidt
authors.forename: T
authors.initials: T
authors.lastname: Boulain
authors.forename: C
authors.initials: C
authors.lastname: Brun-Buisson
mesh_terms: D000328:Adult; D001424:Bacterial Infections / Q000097:blood / Q000175:diagnosis* / Q000503:physiopathology; D015415:Biomarkers; D002116:Calcitonin / Q000097:blood*; D015740:Calcitonin Gene-Related Peptide; D005260:Female; D005602:France; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000175:diagnosis* / Q000503:physiopathology / Q000821:virology; D008297:Male; D008875:Middle Aged; D011014:Pneumonia / Q000175:diagnosis* / Q000503:physiopathology / Q000821:virology; D011498:Protein Precursors / Q000097:blood*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index
chemical_list: D015415:Biomarkers; C000606589:CALCA protein, human; D011498:Protein Precursors; D002116:Calcitonin; D015740:Calcitonin Gene-Related Peptide